A large number of products intended to replace red lead and pigments based on zinc chromate as corrosion inhibitors have already been proposed These substitute products contain, as a rule, metal-containing organic compounds.
Thus, for example, DE-C-25 02 781 describes zinc salts and lead salts and mixtures of these salts based on 5-nitroisophthalic acid as rust-inhibiting additives for coating materials. Among the salts described in this patent, the zinc salt of 5-nitroisophthalic acid in particular is used industrially. However, a disadvantage of the products described in DE-C-25 02 781 is that their action and range of uses are limited. Thus, for example, one complaint is that the action in aqueous coating systems is insufficient.
The zinc salts and lead salts described in DE-A-28 07 698 and 28 24 508 exhibit similar behavior.